Tire crown reinforcement

Abstract

A tire with radial carcass reinforcement, having a crown reinforcement which includes at least two working crown plies made of inextensible cables, crossed from one ply to the other, and an additional ply, axially continuous and formed of undulating metallic elements orientated essentially parallel to the circumferential direction and positioned between the working plies.

I claim:  
     
       1. A truck tire with radial carcass reinforcement, having a crown reinforcement comprising at least two working crown plies made up of inextensible wire reinforcing elements, crossed from one ply to the next by forming opposite but equal angles with the circumferential direction ranging between 10° and 60°, and an axially continuous additional ply, the additional ply being placed between radially adjacent ones of the at least two working crown plies and being made up of wire reinforcing elements of greater diameter than that of the reinforcing elements of the radially adjacent ones of the working plies and having an axial width equal to at least 50% of the maximum axial width of the carcass reinforcement, wherein the reinforcing elements of the additional ply are steel and are corrugated in the plane of the ply, the corrugations being parallel to one another, in phase and oriented parallel to the circumferential direction, so that the ratio of amplitude to wavelength of the corrugated elements decreases axially from the center to the edges of said additional ply, reaching a minimum at said edges. 
     
     
       2. A tire according to  claim 1 , in which the ratio of amplitude to wavelength of the corrugations of the reinforcing elements of the additional ply ranges between 2% and 15%. 
     
     
       3. A tire according to  claim 1  in which the ratio of amplitude to wavelength of the corrugated elements progressively decreases radially from the center of the ply to its edges. 
     
     
       4. A tire according to  claim 1  in which the radially-innermost working crown ply has a meridian curvature roughly equal to the meridian curvature of the subjacent carcass reinforcement and is placed parallel to said carcass reinforcement, the additional ply is placed radially adjacent to the radially-innermost working crown ply, triangular sections of rubber are interposed between the axial edges of the radially-innermost working crown ply and the additional ply, and the curvature of the additional ply is roughly zero. 
     
     
       5. A tire according to  claim 1  in which the crown reinforcement further includes a protection ply, radially situated above the radially-outermost working crown ply, and comprising straight elastic steel wire cords, circumferentially oriented at an angle α in the same direction as an angle B of the elements of the radially-outermost working crown ply, and the axial width of the protection ply is equal to at least the axial width of the additional ply. 
     
     
       6. A track tire with radial carcass reinforcement, having a crown reinforcement comprising at least two working crown plies made up of inextensible wire reinforcing elements, crossed from one ply to the next by forming angles with the circumferential direction ranging between 10° and 60°, and an axially continuous additional ply, the additional ply being placed between radially adjacent ones of the at least two working crown plies and being made up of wire reinforcing elements of greater diameter than that of the reinforcing elements of the radially adjacent ones of the working plies and having an axial width equal to at least 50% of the maximum axial width of the carcass reinforcement, wherein the reinforcing elements of the additional ply are steel and are corrugated in the plane of the ply, the corrugations being parallel to one another, in phase and oriented parallel to the circumferential direction, so that the ratio of amplitude to wavelength of the corrugated elements decreases axially from the center to the edges of said additional ply, reaching a minimum at said edges, and in which the crown reinforcement further includes a protection ply, radially situated above the radially-outermost working crown ply, and comprising straight elastic steel wire cords, circumferentially oriented at an angle α in the same direction as an angle β of the elements of the radially-outermost working crown ply, and the axial width of the protection ply is equal to at least the axial width of the additional ply.